Crank-Drive Subaru Build

Discussion in 'Performance Mods' started by, Jan 31, 2010.

  1. Hello all,

    Just thought I'd post a pic and a link to my current project. It's a motorized touring bike that i designed and built from scratch. The frame is 4130 steel, fillet brazed construction.

    The drive system is a subaru EH035 mounted to a Staton 18.75:1 gearbox and driven through a left side crank. Yes, this means you have to pedal when using the engine (the engine acts like the stoker on a tandem) but since i like to pedal anyway, this isn't a problem.

    At 6000 rpm this setup will give me my preferred 90rpm pedal cadence and a speed range of 4mph to 32mph depending on the gear i'm in. I just got the engine mounted up and running yesterday, so no word yet on how it rides. Hopefully by the end of the week I'll have it streetable. More pics on my blog here:

    Attached Files:

    Last edited by a moderator: Feb 24, 2010

  2. give me vtec

    give me vtec Active Member

    thats pretty cool... I like the way you think.
  3. professor

    professor Active Member

    Nice job!
  4. robin bird

    robin bird Member

    That is a great concept--nice job!!
  5. ibdennyak

    ibdennyak Guest

    Nice design. Like the way the frame has space to mount the engine. Wonder if a freewheel crank could be adapted. I like it.
  6. Freewheel pedaling

    That's actually how I have it set up. It's a 16-tooth freewheel for 3/32 chain, so pedaling is pretty low-drag. Pedaling backwards is another story as there's quite a bit of resistance, but riding without the engine or when the clutch is disengaged, is like a regular bike or, more accurately, like pedaling a tandem without the stoker on the back.

    As for the freewheeling capability (by driving on the right side) I decided against it for a few reasons. One, because I do like to pedal, and view the engine as an assist. Two, because this is intended for multi-state tours, I figure it's always better in the eyes of the law to be seen pedaling and this way I can't cheat and get caught by the police cruising by like a motorcyclist rather than a bicyclist. And three, I liked the fixed drive because it makes the bike trickier to ride and I enjoy machinery that takes awhile to master.

    That said, if you wanted a freewheeling (at the cranks) drive, you could use the staton inside drive and drive to the right side instead of the left.
  7. robin bird

    robin bird Member

    As long as you dont lock your feet in !!
  8. mabman

    mabman Member

    Montana doesn't have an automatic/no shift law but you may want to check in with the other states you plan to tour to for their regs if you are trying to apease the polease.

    Nice looking bike though and have fun with it.
  9. Chris Crew

    Chris Crew Member

    That's a nice looking build and a very unusual piece of bicycle machinery.
  10. It Runs

    It runs, and well. Very fun to ride. Tops out at about 30mph with the gearing I have. I don't think the engine will give much more without some healthy pedal-assist, but it's a treat to ride.

    I modified a gripshift shifter to use as a twist throttle. Much nicer that the cheapo twisters I've seen for motorized bikes and not so tall as a motion-pro or other motocross type throttle so I can get my thumbshifters to fit (plus it has lesss cable pull than those.)

    That tank is a temporary thing. Planning to build a tank to go between the top tubes, but it won't be done in time for my trip to San Diego at the end of the month.

    Attached Files:

    Last edited by a moderator: Feb 24, 2010
  11. augidog

    augidog Banned

    what an awesomely awesome piece of ingenuity, wiley :)

    headin' out for a long haul too, good are you packing for the trip?

    gotta love those schwalbe tires, eh?
  12. Baggage

    Thanks for the compliments.

    I've decided to fly to San Diego since I need to be there for a Baja race (not racing on the bicycle, although i do have some ideas for that) and ship the bicycle there so that I can ride it home to Montana after the race. Should be about 1200 miles and I'm hoping to do that in 5 days. I have two large ortlieb panniers for the front rack. I'll be taking a zero-degree down sleeping bag, pad, floorless pyramid shelter, and my regular cycling clothing plus some rain gear (arc'teryx beta AR jacket and some north face bib ski pants) and a pair of heavy mittens.

    For food I have a small stove and a titanium pot/kettle thing. I usually bring an MSR water filter along on my bike trips, so that will probably come along as well.

    For bike stuff I have a Nite Rider rechargeable LED headlight, and a GPS (garmin). I'll have a spare 3/32 chain (same chains on both sides of the bike), 2 extra spark plugs, a multi-tool, chainbreaker, and a quart of oil for daily oil changes (I'll be riding ~10 hours per day at 20-30mph). A tube of loctite, some extra safety wire, a small roll of duct tape, and a bundle of zip-ties. And a 1-gallon gas can for the long nevada highways.

    That's not a complete list but it covers the major items.
  13. augidog

    augidog Banned

  14. mabman

    mabman Member

    Ah yes, the lure of the open road. I have been ogling the adventure cycling site myself and the new Sierra Pacific route with a return trip up the Pacific Coast looks like a really good Wymanesque 4300 mile adventure.

    One thing for sure is that the naysayers will not be able to accuse you of not pedaling with that setup. And that has to be the longest top tube in history! You will get quite a bit of gas volume between the top tube and the drive tube also which is a bonus.

    Prepare well and keep the rubber side down. And don't forget to write.
  15. 80-Mile test Ride

    I took the bike out for an 80-mile test ride last Sunday. It's quite hilly but i averaged 24 mph for the run, which I'm happy with. Bike ran flawlessly right up to the last ten miles when it started throwing the primary drive chain between the gearbox and crank.

    I'd been using a 3/32" 8-speed chain and an aluminum 54-tooth chainring. There was also a lot of snow and slush on the ground so the chain got pretty gritty. I think it was a combination of chain stretch and a bending chainring.

    I've since put on a 50-tooth stainless steel chainring from Surly. I also ground the teeth off the 54-tooth chainring and mounted it with spacers toward the outside to act as a guide (The chain always popped off to the outside.) I also upgraded the chain to a 1/8" chain (KMC 410H) and 14-tooth ACS Freewheel.

    I think I'll need a new cassette at the rear as well as I was getting some skipping when running the 48 - 11 gear combination. I reused a worn out cassette so that's not too surprising.

    I think these mods will do the trick. If I still have problems I'll build a tensioner and some kind of roller guide for the bottom of the chainring. I'll try to get some photos up tomorrow.
  16. mabman

    mabman Member

    Nice, chains get used up pretty fast on mab's. If you keep them extra well lubed, I use T-9 Boeshield in the lg. spray can and have for years, they will last much longer and perform much better. I probably only go 50 miles per chain lube and ofttimes less. Using blank outer rings as a guide is a good solution plus they act as a pants guard also.

    24mph average is not bad at all, in fact you might admit that it is probably just about right to suit most people, especially in long distance touring mode. That is twice as fast as a good touring cyclist can average. I know your were pedaling the whole time because of your setup, but how about that feeling of getting on top of the gear and the motor at the same time? Like riding a tandem with Lance as your stoker, and never gets tired!

    Any idea yet on fuel consumption/mi.?
  17. Mabman: Yeah, I'm very happy with that average speed. Top speed on the flat is about 32mph, after that I run out of gearing, but I wouldn't have enough power (me or the engine) to go with a taller gear anyway. And yes, it's a great feeling to be pedaling along with that much extra power... driving through the cranks definitely synchronizes you with the engine. A neat feeling.

    For the 80-mile trip I used a little less than a 1/4 gallon. So that's what, about 320mpg. Keep in mind I was doing more pedaling than just spinning along, I did add torque to the equation, but I was definately pedaling way way less than I would have been without the engine (and going faster). I'll keep track of mileage on the 1200-mile ride at the end of March. MPG might be a good way to track how much pedaling I'm doing. It's nice to see that between the pedal input and running the power through the gears, I'm doing better than the oft-reported 200mpg with the EH035.
  18. bluesjr

    bluesjr New Member

    perfect saddle choice for the look of your bike. I've got four of those.
  19. Stoney

    Stoney Member

    Anything new to report? How did your trip go?